Air and water barrier

ABSTRACT

A method for decreasing the vapour permeability of a water and air barrier treated substrate that includes treating the substrate with a liquid applied, vapour permeable air and water barrier coating composition comprising a cross-linked polysiloxane dispersion composition.

RELATED APPLICATIONS

This application is the National Stage of International PatentApplication No. PCT/US2014/011048, filed on Jan. 10, 2014, which claimspriority to and all the advantages of United States Patent ApplicationNos. 61/751,428, filed on Jan. 11, 2013, 61/824,152, filed May 16, 2013and 61/905,465, filed Nov. 18, 2013, the contents of which areincorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to the use of a cross-linked polysiloxanedispersion composition as a vapour permeable air and water barrier inthe construction industry.

BACKGROUND

A wide variety of air and water bather systems are used in both newbuilding and remedial construction applications. These barrier systemsare designed to eliminate uncontrolled air and water leakage throughe.g. exterior walls and/or facades enabling the control of e.g.temperature, humidity levels, moisture levels and air quality throughouta building thereby minimising, for example, the possibility of dampproblems and/or the chance of mould growth and poor air quality.

Air barriers are designed to minimise and potentially exclude thepassage of air through, e.g., walls. Water barriers are intended tominimise or exclude the ingress of liquid water from entering a buildingthrough a wall or façade or the like e.g. via capillary action throughcracks, holes or porous materials. The application of such barriersystems to constructions, e.g. cavity wall systems, results in energycost savings and may significantly reduce the ingress of airbornepollutants by substantially reducing the amount of air leakage throughthe exterior walls or facades of a building.

A single material can function as an air and water barrier. Air andwater barriers are typically found in two forms, sheet materials andliquid coating compositions. Each type is usually designed to be either(water) vapour permeable or impermeable. Vapour Impermeable Air andwater barrier coatings effectively block the transfer of water vapourthrough the coating, whilst vapour permeable Air and water barriercoatings control the amount of (water) vapour diffusing through a walldue to variable vapour pressures. Unless prevented or controlled, watervapour will naturally move from a high concentration to a lowerconcentration until it is in balance. Hence, if the vapour pressure ishigh outside the wall and low inside the wall, vapour will be directedinward (and vice versa).

The use of liquid-applied vapour permeable air and water barriers forwall assemblies has only recently significantly increased, not leastbecause air leakage has become recognized as a potential source ofmoisture accumulation in walls. This type of air and water barrier isdesigned to allow moisture vapour to pass through the membrane,promoting diffusion. Determining whether to use a vapour permeable orvapour impermeable air and water barrier (and indeed the degree ofvapour permeability in a selected barrier) is determined through localclimate of the building and the wall design itself i.e. theinter-relationship of the air/water barrier and the insulation layer arelocated in relation to each other in the wall.

Liquid-applied Vapour permeable, air and water barrier coatings can beformed by applying a liquid coating composition onto a suitable internalbuilding construction surface. Liquid-applied air and water barriers arerolled, sprayed or trowelled onto substrates and become part of theinternal structural wall. Because of the way they are applied, there areno fastener holes from the installation where water penetration mayoccur, and there is no potential for mislapping or tearing, as with manysheet materials.

Another important distinction of a liquid-applied air and water barrierin wall assemblies is that they can minimize application error andunintentional air infiltration caused by the over-lapping of sheetapplied materials. The liquid-applied materials are applied and dry orcure as a monolithic membrane around the building envelope.

A variety of both vapour permeable and impermeable air and water barriercoatings are commercially available with the vast majority being organicbased coatings. Unfortunately however, these organic based coatings havecompatibility issues with silicone based materials, such as caulks andweather sealants. The lack of compatibility may lead to the inability touse such silicone materials or the need for complex and potentiallyadditional layers of adhesives, primers and/or adhesion promoters priorto application of silicone caulks and/or sealants etc. This renders theconstruction process more expensive and complicated as it maynecessitate additional labour and more complicated application processesin order to provide a “weather-tight” building.

Another disadvantage with organic coatings of the type currently usedfor currently typically used is that they have poor UV stability (unlikesilicone based materials) and as such cannot be exposed to UV radiationfor extended periods of time during construction without necessitatingre-application of one or more additional coating layer(s), whichobviously adds to the cost of the process. WO2012/064611 proposes asilicone based fluid applied silicone air and water barrier system.

SUMMARY OF INVENTION

It has been surprisingly identified that a one-component cross-linkedpolysiloxane dispersion composition may be used as a liquid applied,vapour permeable air and water barrier coating composition forapplication to internal wall assemblies.

There is provided herein the use of a cross-linked polysiloxanedispersion composition comprising

-   (i) a crosslinked polysiloxane dispersion of a reaction product    of (a) a siloxane polymer having at least two —OH groups per    molecule, or polymer mixture having at least two —OH groups per    molecule, having a viscosity of between 5,000 to 500,000 mPa·s at    25° C., and (b) at least one self catalyzing crosslinker reactive    with (a), and additionally comprising (c) a surfactant and (d)    water;    together with one or more of the following ingredients:-   (ii) one or more fillers selected from the group of colloidal    silica, fumed silica, precipitated silica, diatomaceous earths,    ground quartz, kaolin, calcined kaolin, wollastonite,    hydroxyapatite, calcium carbonate, hydrated alumina, magnesium    hydroxide, carbon black, titanium dioxide, aluminium oxide,    vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate    and slaked lime;-   (iii) one or more stabilizers;-   (iv) one or more rheology modifiers as a liquid applied, vapour    permeable air and water barrier coating composition.

There is also provided herein a method for decreasing the vapourpermeability of a water and air barrier treated substrate by treatingsaid substrate with a liquid applied, vapour permeable air and waterbarrier coating composition comprising a cross-linked polysiloxanedispersion composition comprising

-   (i) a crosslinked polysiloxane dispersion of a reaction product    of (a) a siloxane polymer having at least two —OH groups per    molecule, or polymer mixture having at least two —OH groups per    molecule, having a viscosity of between 5,000 to 500,000 mPa·s at    25° C., and (b) at least one self catalyzing crosslinker reactive    with (a), and additionally comprising (c) a surfactant and (d)    water;    together with one or more of the following ingredients:-   (ii) one or more fillers selected from the group of colloidal    silica, fumed silica, precipitated silica, diatomaceous earths,    ground quartz, kaolin, calcined kaolin, wollastonite,    hydroxyapatite, calcium carbonate, hydrated alumina, magnesium    hydroxide, carbon black, titanium dioxide, aluminium oxide,    vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate    and slaked lime;-   (iii) one or more stabilizers; and-   (iv) one or more rheology modifiers

There is also provided herein a wall assembly comprising a liquidapplied, vapour permeable air and water barrier coating compositioncomprising a cross-linked polysiloxane dispersion composition comprising

-   (i) a crosslinked polysiloxane dispersion of a reaction product    of (a) a siloxane polymer having at least two —OH groups per    molecule, or polymer mixture having at least two —OH groups per    molecule, having a viscosity of between 5,000 to 500,000 mPa·s at    25° C., and (b) at least one self catalyzing crosslinker reactive    with (a), and additionally comprising (c) a surfactant and (d)    water;    together with one or more of the following ingredients:-   (ii) one or more fillers selected from the group of colloidal    silica, fumed silica, precipitated silica, diatomaceous earths,    ground quartz, kaolin, calcined kaolin, wollastonite,    hydroxyapatite, calcium carbonate, hydrated alumina, magnesium    hydroxide, carbon black, titanium dioxide, aluminium oxide,    vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate    and slaked lime;-   (iii) one or more stabilizers; and-   (iv) one or more rheology modifiers.

DESCRIPTION

The liquid applied, vapour permeable air and water barrier coatingcomposition as hereinbefore described is applied at a wet thickness offrom 20 mil (0.508 mm) to 50 mil (1.27 mm), or from 20 to 60 mil (1.524mm) and dries subsequent to application to a dry thickness of from 10mil (0.254 mm) to 25 mil (0.635 mm), or from 10 to 30 mil (0.762 mm).Depending on temperature, humidity and wind conditions, the averagedrying time of the composition is from about 4 to 12 hours and fulladhesion and physical properties will be present after only a few days.

The liquid applied, vapour permeable air and water barrier coatingcomposition as hereinbefore described, once dried on a substrate, meetsthe requirements of ASHRAE 90.1-2010 for ASTM E2178-11, Standard TestMethod for Air Permeance of Building Materials, having an Air Permeance(L/s per m²) of less than 0.006 at a differential pressure of 75 Pa atthicknesses of both 10 mil (0.254 mm) and 15 mil (0.381 mm).

The liquid applied, vapour permeable air and water barrier coatingcomposition, once dried, has a Water Vapour Transmission of greater than7 US Perm (400.49 ng·s⁻¹m⁻² Pa⁻¹) greater than 10 US Perm (572.135ng·s⁻¹m⁻² Pa⁻¹) or greater than 15 US Perm (858.2035 ng·s⁻¹m⁻² Pa⁻¹)according to the Dry Cup Desiccant Method of ASTM E96/E96M-10 for boththe 10 mil (0.254 mm) and 15 mil (0.381 mm) thicknesses, Standard TestMethod for Water Vapour Transmission rate of Materials and in accordancewith Water Vapour Transmission Wet Cup Water Method of ASTM E96/E96M-10,Standard Test Method for Water Vapour Transmission rate of Materials ofgreater than 20 US Perm (1144.27 ng·s⁻¹m⁻² Pa⁻¹), greater than 24 USPerm (1373.12 ng·s⁻¹m⁻² Pa⁻¹) greater than 25 US Perm (1430.3375ng·s⁻¹m⁻² Pa⁻¹) or greater than 30 US Perm (1716.41 ng·s⁻¹m⁻² Pa⁻¹) forcoatings of 10 mil (0.254 mm) thickness and for coatings of 15 mil(0.381 mm) thicknesses.

Furthermore, the liquid applied, vapour permeable air and water barriercoating composition as hereinbefore described, once dried passes theSelf Sealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09.

The wall assembly described herein can comprise the use of the liquidapplied, vapour permeable air and water barrier coating composition asan adhesive to bond elastomer material(s) to construction sheathingsubstrate(s), metal substrate(s) such as painted or unpainted aluminiumsubstrates, galvanized metal substrate(s), wood framing substrate(s) andthe like. Other suitable substrates include, for the sake of example,concrete, oriented strand board (OSB), exterior sheathing, preformedpanels, plywood and wood or steel stud walls.

All viscosity measurements of siloxane materials are made at 25° C.using a recording Brookfield viscometer with Spindle 3 at 2 rpmaccording to ASTM D4287-00(2010) unless otherwise indicated.

The liquid applied, vapour permeable air and water barrier coatingcomposition comprises a crosslinked polysiloxane dispersion containing areverse phase emulsion of:

-   (i) a reaction product of (a) a siloxane polymer having at least two    —OH groups per molecule, or polymer mixture having at least two —OH    groups per molecule, having a viscosity of between 5,000 to 500,000    mPa·s at 25° C., and (b) at least one self catalyzing crosslinker    reactive with (a), additionally comprising (c) a surfactant and (d)    water;    together with one or more of the following ingredients:-   (ii) one or more fillers selected from the group of colloidal    silica, fumed silica, precipitated silica, diatomaceous earths,    ground quartz, kaolin, calcined kaolin, wollastonite,    hydroxyapatite, calcium carbonate, hydrated alumina, magnesium    hydroxide, carbon black, titanium dioxide, aluminium oxide,    vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate    and slaked lime;-   (iii) one or more stabilizers; and-   (iv) one or more rheology modifiers.

The reaction product (i) may additionally comprise one or more additivessuch as in-situ resin reinforcers, stabilizers, e.g. pH stabilizers,fillers and the like may also be added to the mixture. The dispersion isproduced by mixing the above components at a sufficiently high shear totransform the mixture into a gel phase and by then diluting the gel withwater to the desired silicone content.

The siloxane polymers or polymer mixtures (a) used as starting materialsfor the reaction product (i) above have a viscosity between 5,000 to500,000 mPa·s. at 25° C. using a recording Brookfield viscometer withSpindle 3 at 2 rpm according to ASTM D4287-00(2010). The siloxanepolymers are described by the following molecular Formula (1)X_(3-n)R_(n)—YO—(R¹ ₂SiO)_(z)—Y—R_(n)X_(3-n)  (1)where n is 0, 1, 2 or 3, z is an integer from 500 to 5000 inclusive, Xis a hydrogen atom, a hydroxyl group and any condensable or anyhydrolyzable group, Y is a Si atom or an Si—(CH₂)_(m)—SiR¹ ₂ group, R isindividually selected from the group consisting of aliphatic, alkyl,aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl or aromatic aryl groupsand R¹ is individually selected from the group consisting of X,aliphatic, alkyl, alkenyl and aromatic groups.

The siloxane polymer (a) can be a single siloxane represented by Formula(1) or it can be mixtures of siloxanes represented by the aforesaidformula or solvent/polymer mixtures. The term “polymer mixture” is meantto include any of these types of polymers or mixtures of polymers. Asused herein, the term “silicone content” means the total amount ofsilicone in the dispersed phase of the dispersion, from whatever source,including, but not limited to the silicone polymer, polymer mixtures,self catalytic crosslinkers, in situ resin reinforcers and stabilizers.

Each X group may be the same or different and can be a hydrogen atom,hydroxyl group and any condensable or hydrolyzable group. The term“hydrolyzable group” means any group attached to the silicon which ishydrolyzed by water at room temperature. The hydrolyzable group Xincludes hydrogen atom, halogen atoms, such as F, Cl, Br or I; groups ofthe Formula —OT, where T is any hydrocarbon or halogenated hydrocarbongroup, such as methyl, ethyl, isopropyl, octadecyl, allyl, hexenyl,cyclohexyl, phenyl, benzyl, beta-phenylethyl; any hydrocarbon etherradical, such as 2-methoxyethyl, 2-ethoxyisopropyl, 2-butoxyisobutyl,p-methoxyphenyl or —(CH₂CH₂O)₂CH₃; or any N,N-amino radical, such asdimethylamino, diethylamino, ethylmethylamino, diphenylamino ordicyclohexylamino. X can also be any amino radical, such as NH₂,dimethylamino, diethylamino, methylphenylamino or dicyclohexylamino; anyketoxime radical of the formula —ON═CM₂ or —ON═CM′ in which M is anymonovalent hydrocarbon or halogenated hydrocarbon radical, such as thoseshown for T above and M′ is any divalent hydrocarbon radical, bothvalences of which are attached to the carbon, such as hexylene,pentylene or octylene; ureido groups of the formula —N(M)CONM″₂ in whichM is defined above and M″ is hydrogen atom or any of the above Mradicals; carboxyl groups of the formula —OOCMM″in which M and M″ aredefined above or carboxylic amide radicals of the formula —NMC═O(M″) inwhich M and M″ are defined above. X can also be the sulphate group orsulphate ester groups of the formula —OSO₂(OM), where M is as definedabove; the cyano group; the isocyanate group; and the phosphate group orphosphate ester groups of the formula —OPO(OM)₂ in which M is definedabove.

The most preferred X groups of the invention are hydroxyl groups oralkoxy groups. Illustrative alkoxy groups are methoxy, ethoxy, propoxy,butoxy, isobutoxy, pentoxy, hexoxy and 2-ethylhexoxy; dialkoxy radicals,such as methoxymethoxy or ethoxymethoxy and alkoxyaryloxy, such asethoxyphenoxy. The most preferred alkoxy groups are methoxy or ethoxy.

R is individually selected from the group consisting of aliphatic,alkyl, aminoalkyl, polyaminoalkyl, epoxyalkyl, alkenyl organic andaromatic aryl groups. Most preferred are the methyl, ethyl, octyl,vinyl, allyl and phenyl groups.

R¹ is individually selected from the group consisting of X, aliphatic,alkyl, alkenyl and aromatic aryl groups. Most preferred are methyl,ethyl, octyl, trifluoropropyl, vinyl and phenyl groups.

When the siloxane polymer of formula (1) has an average of more than twocondensable or hydrolyzable groups per molecule which are selfcatalytic, it is not necessary to have the self catalytic crosslinkerpresent separately to form a crosslinked polymer. The condensable orhydrolyzable groups on the different siloxane molecules can react witheach other to form the required crosslinks.

The siloxane polymer (a) can be a mixture of different kinds ofmolecules, for example, long chain linear molecules and short chainlinear or branched molecules. These molecules may react with each otherto form a crosslinked network. Such siloxanes, which can take the placeof more conventional crosslinkers, are illustrated by low molecularweight organosilicon hydrides, such as polymethylhydrogensiloxane, lowmolecular weight copolymers containing methylhydrogensiloxy anddimethylsiloxy groups, —(OSi(OEt)₂)—, (ethylpolysilicate),(OSiMeC₂H₄Si(OMe)₃)₄ and (OSi-MeON═CR′₂)₄, where Me is methyl and Et isethyl.

Advantageously, the siloxane polymer (a) also comprises mixtures ofsiloxane polymers of formula (1), exemplified by, but not limited to,mixtures of α,ω-hydroxysiloxy terminated siloxanes and ofα,ω-bis(triorganosiloxy) terminated siloxanes, mixtures ofα,ω-hydroxylsiloxy terminated siloxanes and of α-hydroxy,ω-triorganosiloxy terminated siloxanes, mixtures of α,ω-dialkoxysiloxyterminated siloxanes and of α,ω-bis(tri-organosiloxy) terminatedsiloxanes, mixtures of α,ω-dialkoxysiloxy terminated siloxanes and ofα,ω-hydroxysiloxy terminated siloxanes, mixtures of α,ω-hydroxysiloxyterminated siloxanes and of α,ω-bis(triorganosiloxy) terminatedpoly(diorgano)(hydrogenorgano)siloxane copolymers. The siloxane polymerof the invention can also comprise mixtures of siloxane polymers offormula (1) as described above with liquid, branched methylpolysiloxanepolymers (“MDT fluids”) comprising a combination of recurring units ofthe formulae:(CH₃)₃SiO_(1/2)(“M”)(CH₃)₂SiO(“D”)CH₃SiO_(3/2)(“T”)and containing from 0.1 to 8% hydroxyl groups. The fluids may beprepared by co-hydrolysis of the corresponding chloro- oralkoxy-silanes, as described, for example, in U.S. Pat. No. 3,382,205.The proportion of MDT fluids added should not exceed 50 parts,preferably of 1 to 20 parts by weight, per 100 parts by weight of thepolymer of Formula (1), to achieve improved physical properties andadhesion of the resultant polymers. The siloxane polymer of the presentinvention can also comprise mixtures of siloxane polymers of Formula (1)with liquid or solid, branched methylsiloxane polymeric resinscomprising a combination of recurring units of the formulae:(CH₃)₃SiO_(1/2)(“M”)(CH₃)₂SiO(“D”)CH₃SiO_(3/2)(“T”)SiO_(4/2)(“Q”)and containing from 0.1 to 8% hydroxyl groups, the fluids may beprepared by co-hydrolysis of the corresponding chloro- oralkoxy-silanes, as described, for example in U.S. Pat. No. 2,676,182.The MDTQ fluid/resin may be added in a proportion not exceeding 50parts, preferably of 1 to 10 parts by weight, per 100 parts by weight ofthe polymer of Formula (1) to improve physical properties and adhesionof the resultant polymers. MDTQ fluids/resins can also be mixed with MDTfluids and the polymers of Formula (1).

Finally, the siloxane polymer (a) can comprise mixtures of siloxanepolymers of Formula (1) with compatible organic solvents, to formorganic polymer/solvent mixtures. These organic solvents are exemplifiedby organophosphate esters, alkanes, such as hexane or heptane; higherparaffins; and aromatic solvents, such as toluene or benzene. Thepolymer solvent mixtures can also be added with MDT fluids and/or MDTQfluids to the polymer of Formula (1). Any of the above mixtures ofpolymers or polymer/solvents can be prepared by mixing the ingredientsprior to emulsification or by emulsifying them individually and thenmixing the prepared emulsions.

The at least one self catalytic crosslinker (b) reactive with (a) toform reaction product (i) is present in the amount of 1 to 5 parts byweight per 100 parts of siloxane polymer. The term “self catalyticcrosslinker” means a molecule that has at least one group serving as thecatalytic species. While in certain circumstances only one selfcatalytic crosslinker may be needed to produce an elastomer having thedesired physical properties, those skilled in the art will recognizethat two or more self catalytic crosslinkers may be added to thereaction mixture to achieve excellent results. In addition, the selfcatalytic crosslinker or crosslinkers may be added with a conventionalcatalyst. However, adding the self catalytic crosslinker with aconventional catalyst is not required for the practice of this inventionand the compositions contemplated by this invention may in fact be freeof said conventional catalysts.

Typical self catalytic crosslinkers include tri or tetra functionalcompounds, such as R—Si-(Q)₃ or Si-(Q)₄, where Q is carboxylic, OC(O)R⁴,e.g., acetoxy and R⁴ is an alkyl group of 1 to 8 carbon atoms inclusive,preferably methyl, ethyl or vinyl. Other preferred Q groups are thehydroxyl amines, ON(R⁴)₂, where each R⁴ is the same or different alkylgroup of 1 to 8 carbon atoms inclusive, e.g., ON(CH₂CH₃)₂. Q may also bean oxime group, such as O—N═C(R⁴)₂, where each R⁴ is the same ordifferent alkyl group of 1 to 8 carbon atoms inclusive, e.g.,O—N═C(CH₃)(CH₂CH₃). Further, Q may be an amine group, such as N(R⁵)₂,where R⁵ is the same or different alkyl group of 1 to 8 carbon atomsinclusive or cyclic alkyl group, e.g., N(CH₃)₂ or NH(cyclohexyl).Finally, Q may be an acetamido group, NRC(O)R⁴, where R⁴ is an alkylgroup of 1 to 8 carbon atoms inclusive, e.g. N(CH₃)C(O)CH₃.

In addition, partial hydrolysis products of the aforementioned compoundsmay also function as self catalytic crosslinkers. This would includedimers, trimers, tetramers and the like, for example, compounds of theformula:

where Q and R⁴ are defined in the preceding paragraph.

Also useful as self catalytic crosslinkers are those polymeric orcopolymeric species containing 3 or more (Q) sites located at eitherpendant or terminal positions or both on the backbone of apolydiorganosiloxane molecule. Examples of the pendent group includecompositions of the following formula:

where R⁴ is the same or different alkyl group of from 1 to 8 carbonatoms inclusive and a is 0 or a positive integer and b is an integergreater than 2. In general, polymeric compositions having either pendentor terminal Q groups may be used in the practice of the presentinvention, in particular, compounds of the formula:Q_(3-n)R⁶ _(n)SiO(R⁶ ₂SiO)_(z)SiR⁶ _(n)Q_(3-n)where n is 0, 1, 2 or 3, z is a positive integer, R⁶ is Q orindependently the same or different alkyl chain of 1 to 8 carbon atomsinclusive as long as there are at least three Q groups on the molecule.Q is as described above.

Effective self catalytic crosslinkers are those compounds which formtack free elastomers when mixed with functional silicone polymers in theabsence of additional catalysts such as tin carboxylates or amines. Inthe self catalytic crosslinkers, the acetoxy, oxime, hydroxyl amine(aminoxy), acetamide and amide groups catalyze the formation of Si—O—Sibonds in the reactions contemplated by this invention.

One skilled in the art would recognize that the starting polymer itselfcould be pre-endblocked with self catalytic crosslinking moieties.Optionally, further self-catalytic crosslinkers can be added to suchcompositions.

The surfactant (c) may be selected from nonionic surfactants, cationicsurfactants, anionic surfactants, amphoteric surfactants or mixturesthereof. The surfactant (c) is present in our composition in an amountof 0.5 to 10 parts by weight of siloxane polymer (a) and is preferablypresent in the amount of 2 to 10 parts.

Most preferred are nonionic surfactants known in the art as being usefulin emulsification of polysiloxanes. Useful nonionic surfactants arepolyoxyalkylene alkyl ethers, polyoxyalkylene sorbitan esters,polyoxyalkylene esters, polyoxyalkylene alkylphenyl ethers, ethoxylatedamides and others. The surfactants useful in the instant invention maybe further exemplified by TERGITOL® TMN-6, TERGITOL® 15S40, TERGITOL®15S9, TERGITOL® 15S12, TERGITOL® 15S15 and TERGITOL® 15S20, and TRITON®X405 produced by The Dow Chemical Company of Midland, Mich.; BRIJ® 30and BRIJ® 35; MAKON® 10 produced by STEPAN COMPANY, (Chicago, Ill.); andETHOMID® O/17 produced by Akzo Nobel Surfactants (Chicago, Ill.).

Cationic and anionic surfactants known in the art as being useful inemulsification of polysiloxanes are also useful as the surfactant in theinstant invention. Suitable cationic surfactants are aliphatic fattyamines and their derivatives, such as dodecylamine acetate,octadecylamine acetate and acetates of the amines of tallow fatty acids;homologues of aromatic amines having fatty chains, such asdodecylanalin; fatty amides derived from aliphatic diamines, such asundecylimidazoline; fatty amides derived from disubstituted amines, suchas oleylaminodiethylamine; derivatives of ethylene diamine; quaternaryammonium compounds, such as tallow trimethyl ammonium chloride,dioctadecyldimethyl ammonium chloride, didodecyldimethyl ammoniumchloride and dihexadecyldimethyl ammonium chloride; amide derivatives ofamino alcohols, such as beta-hydroxyethylstearyl amide; amine salts oflong chain fatty acids; quaternary ammonium bases derived from fattyamides of di-substituted diamines, such as oleylbenzylaminoethylenediethylamine hydrochloride; quaternary ammonium bases of thebenzimidazolines, such as methylheptadecyl benzimidazole hydrobromide;basic compounds of pyridinium and its derivatives, such ascetylpyridinium chloride; sulfonium compounds, such asoctadecylsulfonium methyl sulphate; quaternary ammonium compounds ofbetaine, such as betaine compounds of diethylamino acetic acid andoctadecylchloromethyl ether; urethanes of ethylene diamine, such as thecondensation products of stearic acid and diethylene triamine;polyethylene diamines and polypropanolpolyethanol amines.

Cationic surfactants commercially available and useful in the instantinvention include ARQUAD® T27W, ARQUAD® 16-29, ARQUAD® C-33, ARQUAD®T50, ETHOQUAD® T/13 ACETATE, all manufactured by Akzo Nobel Surfactants(Chicago, Ill.).

Suitable anionic surfactants are carboxylic, phosphoric and sulfonicacids and their salt derivatives. The anionic surfactants useful in theinstant invention are alkyl carboxylates; acyl lactylates; alkyl ethercarboxylates; n-acyl sarcosinate; n-acyl glutamates; fattyacid-polypeptide condensates; alkali metal sulforicinates; sulfonatedglycerol esters of fatty acids, such as sulfonated monoglycerides ofcoconut oil acids; salts of sulfonated monovalent alcohol esters, suchas sodium oleylisethionate; amides of amino sulfonic acids, such as thesodium salt of oleyl methyl tauride; sulfonated products of fatty acidsnitriles, such as palmitonitrile sulfonate; sulfonated aromatichydrocarbons, such as sodium alpha-naphthalene monosulfonate;condensation products of naphthalene sulfonic acids with formaldehyde;sodium octahydroanthracene sulfonate; alkali metal alkyl sulphates,ether sulphates having alkyl groups of 8 or more carbon atoms andalkylarylsulfonates having 1 or more alkyl groups of 8 or more carbonatoms.

Anionic surfactants commercially available and useful in the instantinvention include POLYSTEP® A4, A7, A11, A15, A15-30K, A16, A16-22, A18,A13, A17, B1, B3, B5, B11, B12, B19, B20, B22, B23, B24, B25, B27, B29,C—OP3S; ALPHA-STEP® ML40, MC48; STEPANOL™ MG; all produced by STEPANCO., Chicago, Ill.; HOSTAPUR® SAS produced by HOECHST CELANESE;HAMPOSYL® C30 and L30 produced by W.R. GRACE & CO., Lexington, Mass.

Suitable amphoteric surfactants are glycinates, betaines, sultaines andalkyl aminopropionates. These include cocoamphglycinate,cocoamphocarboxy-glycinates, cocoamidopropylbetaine, lauryl betaine,cocoamidopropylhydroxysultaine, laurylsulataine andcocoamphodipropionate.

Amphoteric surfactants commercially available and useful in the instantinvention are REWOTERIC® AM TEG, AM DLM-35, AM B14 LS, AM CAS and AM LPproduced by SHEREX CHEMICAL CO., Dublin, Ohio.

Specifically, anionic surfactants include monovalent alkyl carboxylates;polyvalent alkyl carboxylates; acyl lactylates; alkyl ethercarboxylates; n-acyl sarcosinate; n-acyl glutamates; and fatty acidpolypeptide condensates. Other anionic surfactants are ester linkedsulfonates, such as alkyl sulfo esters; taurates; sulfosuccinates, suchas monoester, diester (both symmetrical and unsymmetrical), ethoxylatedmonoalkyl sulfosuccinates, alkyl amide ½ ester sulfosuccinate;sulfosuccinamates; sulfonated ethers, (Na cocoglycerol ether sulfonate);linear alkylbenzenesulfonates; benzene, toluene, xylene, cumenesulfonate; ligninsulfonates, such as sulfonated polymers having numberaverage molecular weights of 1,000-20,000; petroleum sulfonates, such aspetroleum fractions of differing molecular weights reacted with oleum orH₂SO₄ to sulfonate; paraffin sulfonates, such as sulfoxidation ofn-paraffins via UV/SO₃ secondary alkane sulfonates C₁₄-C₁₈ (e.g.HOECHST™ SAS); [alpha]-olefin sulfonates; alkylnapthalene-sulfonates;diphenyl oxide sulphonates and linear alkylpolyethersulfonates.

Specific non-ionic surfactants include ethoxylated alcohols, ethoxylatedesters, polysorbate esters, ethoxylated amides; polyoxypropylenecompounds, such as propoxylated alcohols, ethoxylated/propoxylated blockpolymers and propoxylated esters; alkanolamides; amine oxides; fattyacid esters of polyhydric alcohols, such as ethylene glycol esters,diethylene glycol esters, propylene glycol esters, glyceryl esters,polyglyceryl fatty acid esters, sorbitan esters, sucrose esters andglucose esters.

Specific cationic surfactants include monoalkyl quaternary ammoniumsalts, which are hydroxylated or ethoxylated, propoxylated; dialkylquaternary ammonium compounds; amidoamines; and aminimides. Specificamphoteric surfactants include N-substituted alkyl amides (i.e. fattyacid plus aminoethanolamines, e.g., cocoamphoglycinate orcocoamphocarboxyglycinate); N-alkyl betaines, including alkylamidobetaines; sulfobetaines, such as laurylsultaine,cocoamidopropylhydroxysultaine; N-alkyl-b-aminopropionates, such aslauraminopropionic acids.

Specific silicone surfactants which improve high temperature stabilityinclude branched or linear polyoxyalkylenes. Specific fluorosurfactantsinclude those selected from anionics (such as carboxylates andsulfonics), non-ionics and amphoterics.

The selection of the surfactant in the present invention also influencesthe clarity of the elastomeric film resulting from the evaporation ofwater from the dispersion. To obtain clear elastomers from siliconelattices, the refractive index must be matched in the final film betweenthe crosslinked siloxane phase and the surfactant/residual water phase.The term “crosslinked siloxane phase” refers to the plurality ofcrosslinked siloxane particles remaining after water has evaporated toform an elastomeric film. The term “surfactant/residual water phase”refers to amount of residual surfactant and water remaining in theelastomeric film after the evaporation of substantially all the waterfrom the dispersion.

In addition to adding the surfactant to the siloxane polymer, themixture also includes a predetermined amount of water. The water ispresent in the mixture in an amount of 0.5 to 30 parts by weight ofsiloxane polymer and is preferably present in the amount of 2 to 10parts. Water may also be added after mixing, in any amount, to dilutethe gel phase.

The reaction product (i) may additionally comprise one or more additivessuch as in-situ resin reinforcers, stabilizers, e.g., pH stabilizers,fillers and the like may also be added to the mixture. The reactionproduct (i) is produced by mixing the above components at a sufficientlyhigh shear to transform the mixture into a gel phase and by thendiluting the gel with water to the desired silicone content.

The reaction product of (a) a siloxane polymer having at least two —OHgroups per molecule, or polymer mixture having at least two —OH groupsper molecule, having a viscosity of between 5,000 to 500,000 mPa·s at25° C., and (b) at least one self catalyzing crosslinker reactive with(a), additionally comprising (c) a surfactant and (d) water; typicallycomprises, excluding additives (i.e. on the basis that the (product of(a)+(b))+(c)+(d) is 100% by weight), 70 to 90% by weight of the reactionproduct of (a)+(b), 3 to 10% by weight of (c) and 7 to 20% by weight ofcomponent (d). Alternatively, excluding additives (i.e. on the basisthat the (product of (a)+(b)+(c)+(d) is 100% by weight), 80 to 90% byweight of the reaction product of (a)+(b), 3 to 8% by weight of (c) and7 to 15% by weight of component (d).

In addition, in situ resin reinforcers, such as methyltrimethoxy silane,vinyltrimethoxy silane, tetraethyl orthosilicate (TEOS), normalpropylorthosilicate (NPOS) may be added with the self catalyzingcrosslinker. It is believed that adding in situ resin reinforcers to thepolydiorganosiloxane/self catalytic crosslinker mixture forms an in situresin having a highly branched and crosslinked structure, which resultsin improved physical properties of the elastomer, particularly thetensile, elongation and hardness properties. It also results in improvedclarity of the resulting elastomer.

Stabilizers may also be added to the composition. These may comprise anysuitable stabilizer, for example a pH stabilizer or any aminosilanecontaining polymeric or neat aminosilane will function as a stabilizer.Neat aminosilanes include compounds of the formula(R⁴O)_(3-n)R⁴ _(n) nSiQ¹NR⁴ _(y)H_(2-y)where n and y are independently 0, 1 or 2; R⁴ is the same or differentalkyl chain of 1 to 8 carbon atoms inclusive, Q¹ is (CH₂)_(z) or{(CHAN(R⁴)}_(w), where z is an integer from 1 to 10 and w is from 0 to 3inclusive.

Polymeric amino silanes may also be used in the practice of the presentinvention, such as reaction products of silanol functional siloxanefluids and aminosilanes or silanol functional siloxane fluids andalkoxysilanes and aminosilanes. For example, one useful polymeric aminosiloxane particularly useful has the formula:

where z is from 3 to 40.

To prepare the compositions of the instant invention, siloxane polymer(a) and the self catalyzing crosslinker (b) are mixed. Water (d) andsurfactant (c) are then added to the siloxane polymer (a) and the selfcatalyzing crosslinker (b) is mixed in until a high solids gel phase isformed. Any type of mixing equipment may be used including low shearmixing equipment, such as Turrello™, Neulinger™ or Ross™ mixers. The gelwill also exhibit excellent shelf stability and may be stored for longperiods of time or even transported if required. The other ingredientsof the composition may be introduced during the preparation of thepre-cured dispersion or alternatively may be added into the compositionin any suitable order prior to use and after mixing, the resultingcomposition may be diluted with water to the desired silicone content.Both the dispersion alone and the composition may be stored for longperiods of time and will exhibit excellent freeze/thaw stability.

The cross-linked polysiloxane dispersion composition may then be mixedwith the other ingredients prior to use or dispensed and will form anelastomeric film upon the evaporation of water. The method of treating asubstrate may include applying the cross-linked polysiloxane dispersionto the substrate. As such, the method of treating a substrate mayfurther comprise evaporating water from the cross-linked polysiloxanedispersion composition after the cross-linked polysiloxane dispersioncomposition is applied to the substrate to form a silicone latexelastomer on the substrate. The step of evaporation of water may beperformed under ambient, or atmospheric conditions at the location ofthe substrate when the cross-linked polysiloxane dispersion compositionis applied. Alternatively, the step of evaporation of water may beperformed under artificially heated conditions, produced by one or moreheaters.

Once prepared, the aforementioned reaction product (i) may be mixed withthe other ingredients of the composition in any suitable order. It willbe appreciated that all compositions determined by wt % add up to atotal of 100 wt %. The cross-linked polysiloxane dispersion compositionwill typically comprise from 30 to 80 wt %, alternatively 30 to 60 wt %,alternatively 35 to 50 wt % of reaction product (i) as hereinbeforedescribed.

The cross-linked polysiloxane dispersion composition also comprises oneor more fillers. Suitable fillers include, for the sake of example,colloidal silica, silica powders made by combustion (fumed silica) andprecipitation (precipitated silica), semi-reinforcing agents, such asdiatomaceous earths or ground quartz. Nonsiliceous fillers may also beadded, such as, calcium carbonate, hydrated alumina, magnesiumhydroxide, carbon black, titanium dioxide, aluminium oxide, vermiculite,zinc oxide, mica, talcum, iron oxide, barium sulphate, slaked lime,kaolin, calcined kaolin, wollastonite, and hydroxyapatite.

Other fillers which might be used alone or in addition to the above,include aluminite, calcium sulphate (anhydrite), gypsum, calciumsulphate, magnesium carbonate, clays such as aluminium trihydroxide,graphite, copper carbonate, e.g., malachite, nickel carbonate, e.g.,zarachite, barium carbonate, e.g., witherite and/or strontium carbonate,e.g., strontianite; aluminium oxide, silicates from the group consistingof olivine group; garnet group; aluminosilicates; ring silicates; chainsilicates; and sheet silicates. The olivine group comprises silicateminerals, such as, but not limited to, forsterite and Mg₂SiO₄. Thegarnet group comprises ground silicate minerals, such as, but notlimited to, pyrope; Mg₃Al₂Si₃O₁₂; grossular; and Ca₂Al₂Si₃O₁₂.Aluninosilicates comprise ground silicate minerals, such as, but notlimited to, sillimanite; Al₂SiO₅; mullite; 3Al₂O₃.2SiO₂; kyanite; andAl₂SiO₅. The ring silicates group comprises silicate minerals, such asbut not limited to, cordierite and Al₃(Mg,Fe)₂[Si₄AlO₁₈]. If necessary,liquid alkoxysilanes which are soluble in the siloxane polymer (a) mayalso be added with the filler to compatibilise the filler with thesiloxane polymers.

The selection and addition of particular fillers to our compositions,such as certain types of silicas, may improve the physical properties ofthe resulting elastomer, particularly tensile properties, elongationproperties, hardness and heat stability.

Typically the filler(s), when present are present in an amount of from10 to 200 weight parts of filler per 100 wt parts of siloxane polymer(a), alternatively from 15 to 100 weight parts of filler per 100 wtparts of siloxane polymer (a). Hydrophobing agents may be provided totreat the aforementioned filler(s) to render them hydrophobic andtherefore more easily mixed with reaction product (i) the hydrophobingagents may be for example silanes, e.g., alkoxy silanes, silazanes andor short chain (2-20) organopolysiloxanes or alternatively stearates orthe like.

Elastomers containing ammonium stabilized silicas are heat stable, whilesodium stabilized silicas are not. Acidic silicas, (those containing H⁺as a stabilizer) also yield heat stable elastomers. In general,colloidal or dispersed silica which is not stabilized by Group IA or IIAelements of the periodic chart, will also yield heat stable elastomers.Volatile organic amines and volatile inorganic bases are useful asstabilizers for silicas that would yield heat stable elastomers, e.g.,(R⁷)_(3-x)N(H)_(x), where x=0, 1, 2 or 3, R⁷ is an alkyl or aryl group,such as (CH₃)₂NH or R⁷ is an alcohol group, such as N(CH₂CH₂OH)₃ orNH(CH₂CH₂OH)₂. The volatile organic amines include cyclohexylamine,triethylamine, dimethylaminomethylpropanol, diethylaminoethanol,aminomethyl propanol, aminobutanol, monoethanolamine,monoisopropanolamine, dimethylethanolamine, diethanolamine,aminoethylpropanediol, aminomethylpropanesiol, diisopropanolamine,morpholine, tris(hydroxymethyl)aminomethane, triisoproanolamine,triethanolamine, aniline and urea. In addition to the volatile organicamines, volatile inorganic bases, such as ammonia and ammoniumcarbonate, also yield heat stable elastomers.

The composition may also contain one or more rheology modifiers, suchas, natural and modified natural materials, such as, for example starch,modified starch, cellulose, modified cellulose, proteins, and modifiedproteins. Alternatively, the rheology modifiers may be syntheticincluding, for example, (optionally hydrophobically treated) alkaliswellable emulsions of homo-polymers of (meth)acrylic acids andcopolymers thereof with methacrylate esters, hydrophobically modifiedethoxylated urethane resin, dimeric and trimeric fatty acids and/orimidazolines. Furthermore, the rheology modifiers, when utilized, arepresent in an amount of from 0.25 wt % to 5 wt % of the composition.

The composition may also comprise one or more pigments, such as carbonblack or titanium dioxide, and may also be added as fillers. Since thesefillers are only intended to affect the color of the cured siliconelatex elastomer, they are typically added at 0.1 to 20 weight parts,preferably from 0.5 to 10 weight parts, per 100 weight parts of siloxanepolymer. Titanium dioxide has been found to be particularly useful as anultraviolet light screening agent.

The composition may also comprise additional additives, such aspreservatives, buffers, fire retardants, coalescents, disinfectants,corrosion inhibitors, antioxidants, antifoams and biocides (optionallyencapsulated), antifreeze materials, such as polypropylene glycol and/orbuffers.

Those skilled in the art will recognize that these crosslinked, oil inwater dispersions may be prepared in other ways. For instance, thesiloxane polymer and self catalytic crosslinker mixture may be added toa surfactant and water solution and then emulsified using colloid mills,homogenizers, sonolaters or other high shear devices as described inU.S. Pat. Nos. 5,037,878 and 5,034,455.

The dispersion may be formed by either a batch process, as describedabove, or a continuous process. If a continuous process is used, then alow shear dynamic mixer or static mixer is preferred.

The liquid coating may be spray-applied, brushed, rolled, trowelled orotherwise coated onto a substrate although spraying techniques arepreferred. Once applied as a coating on the substrate the compositionwill form an elastomeric film upon the evaporation of water although itis to be noted that no cure reaction takes place upon application to asubstrate the coating merely dries on the substrate surface, typicallythrough water evaporation.

Also given that the siloxane is pre-cured it was believed that suchcompositions would be unable to successfully pass tests such as the SelfSealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09 because it was not expected that the film would be able toself-heal in order to maintain its integrity and prevent water ingressetc. In both cases the composition as hereinbefore described hasunexpectedly proven to meet the necessary requirements for these twomatters. Furthermore, the coating as described herein has the addedadvantage over many currently available air/water barrier coatings inthat it is compatible with other silicone based products such asadhesives, caulks and sealants.

Hence, the present composition may be used as a vapour permeable air andwater barrier coating in any building requiring same, for example,cavity wall systems in climatic regions where the provision of air andwater barriers which are permeable to (water) vapour are beneficial andwhen the structure of the cavity wall is designed appropriately. As theskilled man appreciates, cavity wall systems vary in structure toaccommodate the local climate, i.e., the relative positions of theinsulation and air/water barrier in the cavity wall system as thecoating is provided to enable the diffusion of water vapour through thecoating and is intended to be applied on a substrate with a view toprevent the risk of moisture getting trapped in the wall cavity. Thecomposition herein is particularly suited for environments in which highlevels of (water) vapour permeability are advantageous because of thesurrounding climate. As will be seen below the composition herein has abetter Water Vapour Transmission in accordance with ASTM E96/E96M-10 DryCup Desiccant Method, of greater than 7 US Perm (400.49 ng·s⁻¹m⁻² Pa⁻¹)and a Wet Cup Method of greater than 24 US perms for coatings of 15 mil(0.381 mm) It is particularly to be noted that these dry cup results forcoatings of 15 mil (0.381 mm) thickness are surprisingly different fromthe product described in WO2012/064611.

The composition herein may be used as a vapour permeable air/waterbarrier on any suitable substrate, such as for example masonrysubstrates, such as concrete block, fluted block, brick, stucco,synthetic stucco, poured concrete, precast concrete, insulation finishsystems (EIFS), shotcrete, gypsum as well as gypsum board, wood, plywoodand any other interior surfaces requiring said barrier coating. Thesubstrate may be located on either the interior or exterior of loadbearing supports of a wall assembly. Indeed the substrate may be theaforementioned load bearing support, e.g., a concrete masonry unit(CMU). Before the cross-linked polysiloxane dispersion compositiondescribed above is dried, the wall assembly comprises cross-linkedpolysiloxane dispersion composition disposed on the substrate asdescribed above. However, after the cross-linked polysiloxane dispersioncomposition is dried, the wall assembly comprises a vapour permeable airand water barrier coating formed from drying or evaporating thecross-linked polysiloxane dispersion composition described above.

It is known that silicones have excellent overall durability, includingultraviolet radiation exposure on buildings. An air barrier needs towithstand a certain amount of ultraviolet radiation during the timeperiod after installation and before the exterior building façade isinstalled. Some air barriers have a limited exposure time before themanufacturer recommends covering the air barrier with the buildingfaçade. As the current invention is a silicone-based material theultraviolet durability allows the air barrier to be exposed indefinitelyto the atmosphere or for at least a long period of time which couldenable greater flexibility during construction or in the event of delayson the jobsite.

Many vapour permeable air and water barrier coatings are organic solventbased and therefore have problems meeting today's increasingly stringentenvironmental volatile organic compounds requirements. The fact that thecomposition as hereinbefore described is a water based material resultsin the present composition avoiding such problems. Coating materialsmust meet the ever increasingly stringent environmental requirements inorder to be allowed to be placed on the market in countries and statesaround the world. In the United States specific limits must be met forvolatile organic compounds (VOCs). At the time of writing, the strictestof these limits is the South Coast Air Quality Management District Rule1113. In order to meet the requirements of this Rule, liquid applied,vapour permeable air and water barrier coatings must have VOCs less than50 g/L in order to be used in areas regulated by SCAQMD. The material ashereinbefore described has a 1 gram of VOCs per litre of material whenmeasured using the exclusive method and 2 g/L inclusively. Many othermaterials (especially those which are solvent based) do not meet thisrequirement, but the present composition has a VOC of <2 g per litre inaccordance with (US Environmental Protection Agency (EPA) Method 24.

Whilst the majority of commercially available coatings cure to a minimum40 mil (1.016 mm) thickness and often require even thicker coatings thepresent invention may be coated on a substrate at a thickness of 10 mil(0.254 mm) to 30 mil (0.762 mm) and still meets all necessary tests aswill be noted in the following examples avoiding problems encounteredwith many commercial alternatives which require significantly thickercoatings (e.g., >50 mil (1.27 mm)) especially as it is recognised thatvery thick coatings of air/water barriers can interfere with diffusion.It is to be noted that the present composition contains a pre-curedpolysiloxane network prior to application and as such the coating isapplied and merely dries on the substrate rather than having theadditional need to cure. The composition as hereinbefore described issuitable for providing an evenly distributed coating across the wholesurface of a substrate, even when said substrate has an uneven surfaceand/or is porous.

The coating composition as described herein, when applied onto asubstrate, provides substrates with long-term protection from air andwater infiltration, normal movement imposed by seasonal thermalexpansion and/or contraction, ultra-violet light and the weather. Itmaintains water protection properties even when exposed to sunlight,rain snow or temperature extremes. Indeed the composition when tested inaccordance with ASTM 1970-09, section 8.6 for low temperatureflexibility using a sample having a 15 mil (0.381 mm) coating thickness,passed the test proving that the composition, once applied, remainsflexible at low temperatures.

One particular advantage over other products is that the coatingcomposition as described herein, when applied onto a substrate, may beexposed for an extended or even indefinite period of time prior to theapplication of exterior cladding.

The present invention will now be described in detail by way of thefollowing Examples in which all viscosity measurements were taken at 25°C. using a recording Brookfield viscometer with Spindle 3 at 2 rpmaccording to ASTM D4287-00(2010) unless otherwise indicated.

Preparation of Composition

The preformed silicone latex emulsion was prepared by introducing about2 parts by weight of

(where each R⁴ group is a methyl group) into 100 parts by weight of ahydroxyl dimethyl silyl terminated polydimethylsiloxane having aviscosity of 50,000 mPa·s at 25° C. using a recording Brookfieldviscometer with Spindle 3 at 2 rpm according to ASTM D4287-00(2010) in aTurrello mixer. 4 parts of a 1:1 solution of water and surfactant(TERGITOL TMN-10) were then added and the resulting mixture was mixeduntil a high solids emulsion gel was formed. The resulting pre-formedsilicone latex emulsion was then suitable for mixing with the otheringredients of the composition.

A composition as hereinbefore described was then prepared by mixing thefollowing ingredients together:

-   40.8 wt % of the previously prepared preformed silicone latex    emulsion-   23.14 wt % of colloidal silica-   9.72 wt % ultrafine calcium carbonate-   9.72 wt % Dupont Ti-PURE® R-706 titanium dioxide pigment-   14.3 wt % water-   0.75 wt % TERGITOL TMN-10 surfactant-   0.91 wt % of rheology modifier-   0.66 wt % of antifoam

Once the composition was thoroughly intermixed it was de-aired undervacuum and filtered prior to use.

Air Permeance

Samples of the composition prepared as described above were then appliedonto an air permeable polyethylene (PE) substrates in the case of 8 mil(0.2032 mm) samples and polyethylene substrates in the case of 15 mil(0.381 mm) thickness samples and allowed to dry to the thickness valuesidentified in Table 1 below. The resulting dry silicone elastomericcoatings were removed from respective substrates and tested according toASTM E2178-11, Standard Test Method for Air Permeance of BuildingMaterials (i.e. the rate of air flow (L/s), per unit area (m²) of amaterial per unit static pressure differential (Pa)), however the testpieces used for the 8 mil (0.02032 mm) thickness samples had an overallsize of 360 mm length x 360 mm (width) instead of 1m×1m specified. Ascaled pressure chamber with an internal opening of 305 mm×305 mm wastherefore used to conduct the 8 mil (0.2032 mm) thickness samples. The15 mil (0.381 mm) thickness samples were measured in complete accordancewith ASTM E2178-11, Standard Test.

TABLE 1a Air Permeance Results at a variety of differential Pressuresfor 8 mil (0.2032 mm) thickness sample: Differential Pressure (Pa) AirPermeance (L/s per m²) 25 0.0012 50 0.0021 75 0.0029 100 0.0037 1500.0052 300 0.0096 100 0.0038 75 0.0029 50 0.0020

Current building codes typically set the value required to be below is0.02 L/s per m² at a pressure differential of 75 Pa and as such it willbe appreciated that the composition as hereinbefore described even atsignificantly higher differential pressures serves as an air barrier. Itshould also be appreciated that the thickness of the material at whichthis coating meets this standards is thinner than a majority of thetypical materials used in this market.

TABLE 1b Air Permeance Results at a variety of differential Pressuresfor 15 mil (0.381 mm) thickness sample: Differential Pressure (Pa) AirPermeance (L/s per m²) 25 0.00144 50 0.00312 75 0.00494 100 0.00682 1500.01086 300 0.02428 100 0.00688 75 0.00504 50 0.00326

As with the 8 mil (0.2032 mm) thickness samples it will be appreciatedthat the composition as hereinbefore described even at significantlyhigher differential pressures serves as an air barrier. In this instancethe sample was prepared on an air permeable fibreboard in order towithstand the rigors of the test. It will be appreciated that there is ahigher probability of pin-holes in the fibreboard material that willresult in the higher air permeability. Also, due to the nature of thefibreboard, it is more difficult to ensure such a thin film thickness.Fibreboard absorbs some of the material.

Water Vapour Transmission Rate

In addition the same silicone latex emulsion was tested according toASTM E96/E96M-10, Standard Test Method for Water Vapour TransmissionRate of Materials (i.e. the steady water vapor flow in unit time throughunit area of a body, normal to specific parallel surfaces, underspecific conditions of temperature and humidity at each surface.

TABLE 2a Water Vapour Transmission Results using a sample ashereinbefore described in accordance with ASTM E96/E96M-10: Water VapourWater Vapour Transmission Dry Cup Transmission Wet Cup ThicknessDesiccant Method (US Perm Water Method (US Perm (mil/(mm)) (ng/Pa · s ·m²)) (ng/Pa · s · m²)) 10 (0.254) 7.16 (409.65) 30.34 (1735.86) 15(0.381) 7.03 (402.21) 24.26 (1388) 20 (0.508) 4.77 (272.91) 19.97(1142.56)

The above values were compared with published values for commercialproducts according to the publically available data from the Air BarrierAssociation of America in relation to water vapour transmission valuesmeasured in accordance with ASTM E96/E96M-10 which are provided in Table2b below:

TABLE 2b Water Vapour Transmission Results of Commercial Products inaccordance with ASTM E96/E96M-10 as available from the Air BarrierAssociation of America: Water Vapour Water Vapour Transmission Dry CupTransmission Wet Cup Desiccant Method (US Water Method (US PermCommercial Product Perm (ng s⁻¹ · m⁻² · Pa⁻¹)) (ng s⁻¹ · m⁻² · Pa⁻¹))Momentive SilShield AWB 4.273 (244) 5.493 (314) @ 26 mils (0.66 mm)(wet) WR Grace Perm-A-Barrier VP 0.60 (34.39) 12.9 (741.6) @ 40 mils(1.016 mm) (dry) Henry Air Bloc 31 MR 0.57 (32.0) 36.12 (2066) @ 44 mils(1.12 mm) (dry) Henry Air Bloc 32MR 0.23 (13.0) 1.02 (58) @118 mils(3.00 mm) (wet) Henry Air Bloc 33 MR 0.34 (19.0) 11.4 (652) @ 59 mils(1.50 mm)(dry) Henry Air Bloc 06 WB 0.34 (19.0) 11.4 (652) @ 59 mils(1.50 mm) (dry) Carlisle Barritech VP 0.719 (41.1) 14.295 (817) @ 60mils (1.524 mm) (wet) [40 mils (1.016 mm) (dry)] BASF Enershield HP 0.10(5.81) 17.6 (1004) @ 10 mils (0.254 mm) (wet) Dupont - Tyvek FluidApplied WB 11.48 (656) 24.23 (1384) @ 10 mils (0.254 mm) (wet) ProsocoR-Guard Spray Wrap@ 0.12 (6.86) 3.54 (202) 12 mils (0.305 mm) (wet)Warnock Hersey Sto Gold Coat@ 0.12 (6.86) 3.54 (202) 12 mils (0.305 mm)(wet)

It is important to note that the Water Vapor Permeance value of thematerial as depicted in Table 2a, when tested using the desiccant cupmethod, is greater than other materials in the market (depicted in Table2b), including the material found in Momentive SilShield™ which isbelieved to be the commercial product manufactured by the proprietors ofWO2012/064611, Industry scientists have argued that the desiccant methodis more realistic than the wet cup method because it relies on thetransfusion of vapour from the air through the material and not on astanding cup of water to ensure diffusion of water through the material.The wet cup method allows water droplets to form on the underside of thematerial being tested; this allows vapour to move through the materialvia direct contact. The material is not typically found in areas withstanding water in this application. ICC-ES AC38 for building wrapmaterials used in the same application require only the desiccant testmethod for these same reasons.

Self Sealability

Further samples of coated substrate were analysed in accordance with theSelf Sealability (Head of Water) Test described in Section 8.9 of ASTMD1970-09. This test describes nail sealability requirements ofbituminous roofing systems but is a commonly used standard for airbarrier materials. The test was carried out on samples prepared asrequired by the Test Method, at several coating thicknesses of the driedcoating as hereinbefore described and each coating passed the test asindicated in Table 3 below:

TABLE 3 Thickness mil (mm) Self Sealability 10 (0.254) Pass 15 (0.381)Pass 20 (0.508) Pass

Elastomeric materials do not innately have a self-sealing property. Bydefinition, elastomeric materials will return to their original stateafter being stressed within its elastic range, but that does not meanthat the material will return back to its original state after theelastic range has been surpassed and the material has torn. The factthat the material as hereinbefore described is a pre-cured siliconeemulsion that dries and does not cure upon application, was originallyconsidered to render it very likely to fail the above test because itwas not anticipated that the material would keep a tight enough seal tomaintain the required water head once the dried matrix of the materialwas broken by a nail applied during the test, especially at such lowthicknesses as depicted in Table 3 above. In comparison the materialdescribed in WO2012/064611 differs in that it is a material which curessubsequent to application.

Flame Spread and Smoke Developed Indices Based Upon a Single TestConducted in

Accordance with ASTM E 84-12a

The method, designated as ASTM E 84-12a “Standard Method of Test forSurface Burning Characteristics of Building Materials”, is designed todetermine the relative surface burning characteristics of materialsunder specific test conditions. Results are expressed in terms of FlameSpread Index (FSI) and Smoke Developed (SD).

A composition as hereinbefore described was applied onto a 0.25 inch (6mm) reinforced fibreglass cement board substrate to a thickness ofapproximately 15 mil (0.381 mm) The following tests were carried out inaccordance with ASTM E 84-12a excepting that whilst Section 5.1.9.1 ofASTM E 84-12a specifies a single combination of lamp and photocell tocreate the requisite photometer system, in the present test aspecially-designed, modern photometer system that is utilized by manyother tunnel systems worldwide was used.

Test Results

Flame Spread Index (FSI) gave a value of 10 and Smoke Developed (SD)gave a value of 85.

The air leakage of a sample air barrier comprising the composition ashereinbefore described was determined in accordance with ASTM E2357-11(standard test method for determining air leakage of air barrierassemblies in US) and it gave the results of 0.000007 cfm/ft² at 1.57psf (75.2 Pa) and 0.00003 L/s per m² at 75 Pa. The assembly was alsotested in accordance with CAN/ULC-5742 and it gave the results of aClass 1A rating. ASTM E2357-11 is utilized in an attempt to mimic realworld conditions by preparing two exterior wall mock-ups with onemock-up being a simple wall assembly with sheathing joints and the otherbeing constructed with sheathing joints; roof and foundation tie-ins;brick ties, window openings; and electrical, pipe and ductworkpenetrations. Each of the tie-ins and penetrations is fully sealed withsealant and/or pre-cured extrusions and flashed to the air barrierassembly to ensure it can withstand the simulated conditions. Then bothwall mock-ups were exposed to positive and negative sustained wind loadsas identified within the test method.

The invention claimed is:
 1. A cross-linked polysiloxane dispersioncomposition, for an air and water barrier coating composition,comprising (i) a crosslinked polysiloxane dispersion of: a reactionproduct of (a) a siloxane polymer having at least two —OH groups permolecule, or polymer mixture having at least two —OH groups permolecule, having a viscosity of between 5000 to 500,000 mPa.s at 25° C.,and (b) at least one self catalyzing crosslinker reactive with (a), andadditionally comprising (c) a surfactant and (d) water; together withone or more rheology modifiers and optionally together with one or moreof the following ingredients: (ii) one or more fillers selected from thegroup of colloidal silica, fumed silica, precipitated silica,diatomaceous earths, ground quartz, kaolin, calcined kaolin,wollastonite, hydroxyapatite, calcium carbonate, hydrated alumina,magnesium hydroxide, carbon black, titanium dioxide, aluminium oxide,vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate andslaked lime or a mixture thereof; and (iii) one or more stabilizers;wherein the polysiloxane dispersion composition is a liquid and whereinthe cross-linked polysiloxane dispersion composition, once dried on asubstrate, passes the Self Sealability (Head of Water) Test described inSection 8.9 of ASTM D1970-09.
 2. The cross-linked polysiloxanedispersion composition of claim 1 wherein the air and water barriercoating composition is a vapour permeable air and water barrier coatingcomposition.
 3. The cross-linked polysiloxane dispersion composition ofclaim 1 wherein the cross-linked polysiloxane dispersion composition,when applied on to the substrate at a wet thickness of from 20 mil(0.508 mm) to 60 mil (1.524 mm), dries subsequent to application to adry thickness of from 10 mil (0.254 mm) to 30 mil (0.762 mm).
 4. Thecross-linked polysiloxane dispersion composition of claim 1 wherein thecross-linked polysiloxane dispersion composition, once dried on thesubstrate, meets the requirements of ASTM E2178-11, Standard Test Methodfor Air Permeance of Building Materials, having an Air Permeance (L/sper m²) of less than 0.006 at a differential pressure of 75 Pa atthicknesses of 10 mil (0.254 mm) and 15 mil (0.381 mm).
 5. Thecross-linked polysiloxane dispersion composition of claim 1 wherein thecross-linked polysiloxane dispersion composition once dried, has a WaterVapour Transmission of greater than 7 US Perm (400.5 ng.s⁻¹ m⁻² Pa⁻¹)according to the Dry Cup Desiccant Method of ASTM E96/E96M-10 for boththe 10 mil (0.254 mm) and 15 mil (0.381 mm) thicknesses; and, StandardTest Method for Water Vapour Transmission rate of Materials and inaccordance with Water Vapour Transmission Wet Cup Water Method of ASTME96/E96M-10, Standard Test Method for Water Vapour Transmission rate ofMaterials of greater than 30 US Perm (1716.41 ng.s⁻¹ m⁻² Pa⁻¹) forcoatings of 10 mil (0.254 mm) thickness and greater than 24 US Perm(1373.12 ng.s⁻¹ m⁻² Pa⁻¹) for coatings of 15 mil (0.381 mm) thickness.6. The cross-linked polysiloxane dispersion composition of claim 1wherein the substrate is selected from construction sheathingsubstrate(s), metal substrate(s), masonry substrate(s), galvanized metalsubstrate(s) and wood framing substrate(s) and any combination thereof.7. The cross-linked polysiloxane dispersion composition of claim 1wherein the cross-linked polysiloxane dispersion composition comprises,excluding additives (i.e. on the basis that the (product of (a) +(b))+(c) +(d) is 100% by weight), 70 to 90% by weight of the reactionproduct of (a) +(b), 3 to 10% by weight of (c) and 7 to 20% by weight ofcomponent (d).
 8. A method for decreasing the vapour permeability of awater and air barrier treated substrate by treating a substrate with aliquid applied, vapour permeable air and water barrier coatingcomposition comprising a cross-linked polysiloxane dispersioncomposition comprising (i) a crosslinked polysiloxane dispersion of: areaction product of (a) a siloxane polymer having at least two —OHgroups per molecule, or polymer mixture having at least two —OH groupsper molecule, having a viscosity of between 5,000 to 500,000 mPa.s at25° C., and (b) at least one self catalyzing crosslinker reactive with(a), and additionally comprising (c) a surfactant and (d) water;together with one or more rheology modifiers and optionally togetherwith one or more of the following ingredients: (ii) one or more fillersselected from the group of colloidal silica, fumed silica, precipitatedsilica, diatomaceous earths, ground quartz, kaolin, calcined kaolin,wollastonite, hydroxyapatite, calcium carbonate, hydrated alumina,magnesium hydroxide, carbon black, titanium dioxide, aluminium oxide,vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate andslaked lime; and (iii) one or more stabilizers; wherein the cross-linkedpolysiloxane dispersion composition, once dried on the substrate, passesthe Self Sealability (Head of Water) Test described in Section 8.9 ofASTM D1970-09.
 9. The method in accordance with claim 8 wherein thecross-linked polysiloxane dispersion composition is applied on to thesubstrate at a wet thickness of from 20 mil (0.508 mm) to 60 mil (1.524mm) and dries subsequent to application to a dry thickness of from 10mil (0.254mm) to 30 mil (0.762 mm)).
 10. The method in accordance withclaim 8 wherein the cross-linked polysiloxane dispersion composition,once dried on the substrate, meets the requirements of ASTM E2178-11,Standard Test Method for Air Permeance of Building Materials, having anAir Permeance (L/s per m²) of less than 0.006 at a differential pressureof 75 Pa at thicknesses of both 10 mil (0.254 mm) and 15 mil (0.381 mm).11. The method in accordance with claim 8 wherein the cross-linkedpolysiloxane dispersion composition, once dried on the substrate meetsWater Vapour Transmission Dry Cup Desiccant Method in accordance withASTM E96/E96M-10, Standard Test Method for Water Vapour Transmissionrate of Materials of greater than 7 US Perm, for both the 10 mil (0.254mm) and 15 mil (0.381 mm), and Water Vapour Transmission Wet Cup WaterMethod in accordance with ASTM E96/E96M-10, Standard Test Method forWater Vapour Transmission rate of Materials of 30 US Perm (1716.41ng.s⁻¹ m⁻² Pa⁻¹) for coatings of 10 mil (0.254 mm) thickness and greaterthan 24 US Perm (1373.12 ng.s⁻¹ m⁻² Pa⁻¹) for coatings of 15 mil (0.381mm) thickness.
 12. The method in accordance with claim 8 wherein thesubstrate is selected from construction sheathing substrate(s), metalsubstrate(s), galvanized metal substrate(s), wood framing substrate(s),masonry substrates, or gypsum board, wood, or plywood and anycombination thereof.
 13. The method in accordance with claim 8 whereinthe substrate is an interior or exterior load bearing support or islocated on either an interior or exterior load bearing support of a wallassembly.
 14. The method in accordance with claim 9 wherein thecross-linked polysiloxane dispersion composition comprises, excludingadditives (i.e. on the basis that the (product of (a) +(b)) +(c) +(d) is100% by weight), 70 to 90% by weight of the reaction product of (a)+(b), 3 to 10% by weight of (c) and 7 to 20% by weight of component (d).15. The method in accordance with claim 8 further comprising evaporatingwater from the cross-linked polysiloxane dispersion composition afterthe cross-linked polysiloxane dispersion is applied to the substrate.16. A wall assembly comprising a liquid applied, vapour permeable airand water barrier coating composition applied on a substrate, the vapourpermeable air and water barrier coating composition comprising across-linked polysiloxane dispersion composition comprising (i) acrosslinked polysiloxane dispersion of: a reaction product of (a) asiloxane polymer having at least two —OH groups per molecule, or polymermixture having at least two —OH groups per molecule, having a viscosityof between 5000 to 500,000 mPa.s at 25° C., and (b) at least one selfcatalyzing crosslinker reactive with (a), and additionally comprising(c) a surfactant and (d) water; together with one or more rheologymodifiers and optionally one or more of the following ingredients: (ii)one or more fillers selected from the group of colloidal silica, fumedsilica, precipitated silica, diatomaceous earths, ground quartz, kaolin,calcined kaolin, wollastonite, hydroxyapatite, calcium carbonate,hydrated alumina, magnesium hydroxide, carbon black, titanium dioxide,aluminium oxide, vermiculite, zinc oxide, mica, talcum, iron oxide,barium sulphate and slaked lime; and/or (iii) one or more stabilizers;wherein the cross-linked polysiloxane dispersion composition, once driedon the substrate, passes the Self Sealability (Head of Water) Testdescribed in Section 8.9 of ASTM D1970-09.
 17. The wall assembly inaccordance with claim 16 wherein the cross-linked polysiloxanedispersion composition is applied on to the substrate at a wet thicknessof from 20 mil (0.508 mm) to 60 mil (1.524 mm) and dries subsequent toapplication to a dry thickness of from 10 mil (0.254 mm) to 30 mil(0.762 mm).
 18. The wall assembly in accordance with claim 16 whereinthe cross-linked polysiloxane dispersion composition, once dried on thesubstrate, meets the requirements of ASTM E2178-11, Standard Test Methodfor Air Permeance of Building Materials, having an Air Permeance (L/sper m²) of less than 0.006 at a differential pressure of 75 Pa atthicknesses of both 10 mil (0.254 mm) and 15 mil (0.381 mm).
 19. Thewall assembly in accordance with claim 16 wherein the cross-linkedpolysiloxane dispersion composition, once dried on the substrate, meetsWater Vapour Transmission Dry Cup Desiccant Method in accordance withASTM E96/E96M-10, Standard Test Method for Water Vapour Transmissionrate of Materials of greater than 7 US Perm (572.135 ng.s⁻¹ m⁻² Pa⁻¹),for both 10 mil (0.254 mm) and 15 mil (0.381 mm) thicknesses, and WaterVapour Transmission Wet Cup Water Method in accordance with ASTME96/E96M-10, Standard Test Method for Water Vapour Transmission rate ofMaterials of 30 US Perm (1716.41 ng.s⁻¹m⁻² Pa⁻¹) for coatings of 10 mil(0.254 mm) thickness and greater than 24 US Perm (1373.12 ng.s⁻¹m⁻²Pa⁻¹) for coatings of 15 mil (0.381 mm) thickness.
 20. The wall assemblyin accordance with claim 16 wherein the substrate is selected fromconstruction sheathing substrate(s), metal substrate(s), galvanizedmetal substrate(s) and wood framing substrate(s), concrete masonry, foamplastic insulated sheeting, exterior insulation, pre-formed concrete,cast in place concrete wood framing, oriented strand board (OSB),exterior sheathing, preformed panels, plywood and wood or steel studwalls, roofing felting for roofing membranes, and non-permeable wallassembly.
 21. A wall assembly comprising a silicone latex elastomerapplied on a substrate, the silicone latex elastomer formed fromevaporating water from a composition comprising a cross-linkedpolysiloxane dispersion composition, the polysiloxane dispersioncomposition comprising: (i) a crosslinked polysiloxane dispersion of: areaction product of (a) a siloxane polymer having at least two —OHgroups per molecule, or polymer mixture having at least two —OH groupsper molecule, having a viscosity of between 5000 to 500,000 mPa.s at 25°C., and (b) at least one self catalyzing crosslinker reactive with (a),and additionally comprising (c) a surfactant and (d) water; togetherwith one or more rheology modifiers and optionally together with one ormore of the following ingredients: (ii) one or more fillers selectedfrom the group of colloidal silica, fumed silica, precipitated silica,diatomaceous earths, ground quartz, kaolin, calcined kaolin,wollastonite, hydroxyapatite, calcium carbonate, hydrated alumina,magnesium hydroxide, carbon black, titanium dioxide, aluminium oxide,vermiculite, zinc oxide, mica, talcum, iron oxide, barium sulphate andslaked lime; (iii) one or more stabilizers; wherein the cross-linkedpolysiloxane dispersion composition, once dried on a substrate, passesthe Self Sealability (Head of Water) Test described in Section 8.9 ofASTM D1970-09.